Myc targets

There is intense effort to identify transcriptional targets of the c-Myc proto-oncogene that can account for its role in cell growth and division. In the January 16 Nature Gomez-Roman et al. report that c-Myc directly activates transcription by RNA polymerase III (pol III) (Nature 2003, 421:290-294). Analysis of human fibroblasts and cells from c-myc knockout mice, showed that c-Myc is important for the transcription of pol-III-regulated genes, such as the B2 repetitive gene family, 5S rRNA and tRNA genes. Chromatin immunoprecipitation experiments showed that c-Myc is associated with pol III target genes in vivo. Gomez-Roman et al. report a direct interaction between the regulatory domain of c-Myc and TFIIIB, a pol-III-specific general transcription factor. These new Myc targets help explain how c-Myc regulates growth by activating pol-II- and pol-III-dependant transcriptional programs.